Climate change-induced thawing of permafrost mobilizes previously frozen carbon ofhigh potential reactivity, thereby, fuelling microbiological production of greenhousegases. For this work, an analysis of the quantity, quality, and bioreactivity of DOC instreams from the Stordalen discontinuous permafrost catchment was carried out withstream water samples during the relatively warm summer of 2018.In the study area permafrost is limited to peatland which is present in lowland areas.We hypothesized that (i) peatland-influenced streams have a higher dissolved organiccarbon (DOC) concentration than streams in upland areas of the Stordalen catchment.However, no strong differences in the quantity of DOC between peaty lowland andwell-drained upland areas were found. In general, DOC quantity was lower comparedto levels obtained by previous studies conducted in the area but due to the lack ofdischarge measurements for this study, a comparison with other studies is difficult.Furthermore, no clear pattern was detected regarding the extent of carbon degradation,represented by a small range of the ratio between the isotopically stable carbon-12 andcarbon-13. However, a slightly enhanced degradation in areas located in upland areaswas detected.Additionally, it was predicted that (ii) DOC from upland areas was associated with lowmolecular weight and relatively high bioreactivity compared to DOC derived frompeaty lowland areas. The DOC from all sampled sub-catchments, including the lowlandsampling points in the peat, showed surprisingly high bioreactivity, although the uplandcatchments, where peat was not present, were generally associated with the lowestmolecular weights and highest bioreactivity of the DOC.Upland areas are characterised by a faster turnover of carbon, as oxygen can diffuseinto the shallow organic layer. Thus, (iii) the share of labile C was higher in betterdrained upland areas than in peatland areas. This work showed how quantifiableamounts of low molecular weight DOC can reach streams from permafrost catchmentsduring a warm and dry summer, due to the increasing thickness of the active layer.